1. Field of the Invention
This invention relates to an apparatus for fabrication of cementitious building blocks and more particularly to a self-aligning mold box apparatus for precision casting of interlocking mortarless cementitious building blocks.
2. Description of the Prior Art
The use of building blocks, of the type sometimes referred to as cement blocks, concrete blocks or cinder blocks rather than conventional clay bricks is becoming more widespread. Such building blocks are commonly used by the construction industry for erecting retaining walls, buildings, and the like, and for purposes of this description, all such blocks will hereinafter be referred to as cementitious blocks.
The commonly used cementitious blocks are erected in tiers or rows, which are most often offset, and the individual cementitious blocks are bonded together by mortar which is interposed between the meeting horizontal and vertical surfaces or faces of the blocks. The necessity of such mortar bonding impairs the accuracy and speed with which such blocks can be erected, and requires a relatively high degree of skill to erect a properly aligned and levelled plurality of such blocks.
The degree of skill needed to erect these mortar bonded prior art blocks, not to mention the laborious task, has all but relegated the laying of such blocks to skilled craftsmen.
The laborious task of erecting mortar bonded blocks and the high cost of employing properly skilled craftsmen has prompted the search for mortarless interlocking cementitious building blocks which would ease the problems associated with the prior art blocks.
While the known art includes examples of mortarless interlocking blocks, these known blocks have not proven to be successful for various reasons such as: excessive weight, loose fitting and/or improperly aligned interlocking elements, inadequate provisions for the passage of wiring and pipelines through an erected wall, interference fit between adjacent blocks, and the like.
Many of the problems associated with the prior art interlocking cementitious building blocks are due to the design of the blocks themselves, however, some of these problems arise from the apparatus employed for casting of such blocks.
With regard to the mortarless interlocking cementitious blocks, many of the problems associated therewith have been eliminated and others substantially reduced by a particular block which is fully disclosed in U.S. patent application Ser. No. 903,731 filed on May 8, 1978 by the same inventor.
Regarding fabrication apparatus for mortarless interlocking cementitious blocks, it will be appreciated that the dimensional tolerances of the mortar bonded blocks is not particularly critical in that dimensional inaccuracies and/or inconsistencies existing in such blocks can be compensated for by the craftsman applying more or less mortar during laying of the blocks. Such is not the case in mortarless interlocking blocks as these blocks must be cast, or molded, within specific tolerances in order to achieve proper alignment, leveling and the like.
Therefore, the fabrication, or casting apparatus employed in the manufacture of mortarless interlocking cementitious building blocks must be a precision mechanism which is designed to facilitate relatively frequent inspections for wear brought on by the well known abrasive characteristics of cement, and such apparatus should ideally be provided with easily replaceable parts at the critical wear points in the apparatus. Further, due to the relatively high cost of making such a precision fabricating apparatus, it should ideally be easily modifiable so that the main elements can be employed to form the various types of blocks needed to erect walls such as half-blocks, one-quarter blocks and three quarter-blocks.
In addition, it is a necessity that the various components of the fabrication apparatus be precisely positioned relative to each other during block casting operations to insure proper alignment and positioning of the interlocking elements of the cementitious blocks.
To the best of my knowledge, no prior art fabrication apparatus has been devised or suggested with all of the above described characteristics in general, and no prior art apparatus has been devised or suggested for fabrication of the particular mortarless interlocking cementitious blocks disclosed in the previously referenced U.S. patent application.
Therefore, a need exists for a self-aligning, precision mold box apparatus which overcomes some of the shortcomings of the prior art, and forms a particular type of mortarless interlocking cementitious block.